118 TIMBEES AND THEIR USES 



attentions. Needless to add, such a proceeding 

 causes the death of the tree above the ring. 



The number of wood-loving insects is legion. 

 Some bore only into the bark and, in themselves, 

 do httle harm, but they open up channels favour- 

 able for fungal attacks ; others tunnel in all 

 directions beneath the bark, and their excavations 

 are often so widespread as to cause the bark 

 to leave the tree, with unfortunate restdts ; 

 others, again, actually bore into the wood, 

 some into the pith of the branches, causing the 

 death of these members, others into the stems 

 of the trees, thus damaging the wood for com- 

 mercial purposes. In the United States alone 

 the annual loss caused by insects to forest trees 

 is estimated at one hundred milUon dollars. 



To enumerate the British insects which are 

 known to be injurious to forest trees would 

 occupy more space than we can devote to the 

 subject. There are, for instance, more than fifty 

 common insect pests of the Oak in this country ; 

 the enemies of the Northern Pine are nearly as 

 numerous, whilst those of the Ash, Elm, Beech, 

 Hawthorn, Poplar, Spruce and Larch are many. 

 A brief consideration of some of the worst 

 offenders, arranged in their orders, must suffice. 



Leaf-eating insect pests . Order Coleoptera . 

 A destructive and common forestry pest is the 



